From: Kees Cook <keescook@chromium.org>
Date: Thu, 1 Nov 2018 21:08:07 +0000 (-0700)
Subject: pstore: Remove needless lock during console writes
X-Git-Tag: Ubuntu-4.15.0-61.68~1308
X-Git-Url: https://git.proxmox.com/?p=mirror_ubuntu-bionic-kernel.git;a=commitdiff_plain;h=3a3985d47e3c348360afce2eb62b21982c7ea20d

pstore: Remove needless lock during console writes

BugLink: https://bugs.launchpad.net/bugs/1838700

commit b77fa617a2ff4d6beccad3d3d4b3a1f2d10368aa upstream.

Since the console writer does not use the preallocated crash dump buffer
any more, there is no reason to perform locking around it.

Fixes: 70ad35db3321 ("pstore: Convert console write to use ->write_buf")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
---

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 691032107f8c..7b2f3e270f27 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -594,31 +594,14 @@ static void pstore_unregister_kmsg(void)
 #ifdef CONFIG_PSTORE_CONSOLE
 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 {
-	const char *e = s + c;
+	struct pstore_record record;
 
-	while (s < e) {
-		struct pstore_record record;
-		unsigned long flags;
-
-		pstore_record_init(&record, psinfo);
-		record.type = PSTORE_TYPE_CONSOLE;
-
-		if (c > psinfo->bufsize)
-			c = psinfo->bufsize;
+	pstore_record_init(&record, psinfo);
+	record.type = PSTORE_TYPE_CONSOLE;
 
-		if (oops_in_progress) {
-			if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
-				break;
-		} else {
-			spin_lock_irqsave(&psinfo->buf_lock, flags);
-		}
-		record.buf = (char *)s;
-		record.size = c;
-		psinfo->write(&record);
-		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
-		s += c;
-		c = e - s;
-	}
+	record.buf = (char *)s;
+	record.size = c;
+	psinfo->write(&record);
 }
 
 static struct console pstore_console = {